Strategies for Controlling a Microgravity Isolation Mount

This paper describes the concept of an active vibration Isolation system called a Microgravity Isolation Mount (MGIM), for use on board orbiting spacecraft. The purpose of the Mount is to reduce to an acceptable level the residual accelerations experienced by sensitive experimental payloads, due to vibrational disturbances within the spacecraft environment. The advantages and drawbacks are discussed of introducing an umbilical, to carry electrical power and cooling water between the fixed and free part of the Mount. The interaction between this design factor and the selection of the control technique is considered. Three different techniques for controlling the Mount are compared involving, respectively, feedback of relative displacement measurements only, feedback of payload acceleration and direct control of umbilical extension. The trade-offs between the three methods are described.